title: Development and characterisation of transgenic rice expressing two Bacillus thuringiensis genes.
abstract: BACKGROUND
  Transgenic crops that produce insecticidal toxins from the bacterium Bacillus thuringiensis Berliner (Bt) were first commercialised in 1996. The risk that pests have the potential to evolve resistance to Bt toxins is one of the most serious challenges to this technology. Gene stacking, pyramiding two Bt genes into one variety, is considered to be an effective insect resistance management (IRM) strategy. In this study, insect-resistant rice expressing two Bt genes was developed by sexual crossing, and then characterised.
  
  
  RESULTS
  Homozygous rice lines of two pyramided Bt genes were obtained in the F(3) generation. Quantification of Bt toxin showed that protein concentrations of Cry1Ab, Cry1Ac and Cry2A in the two-gene lines were comparable with their single-gene parents, while the expression of cry1C gene decreased after gene stacking. Four two-gene lines showed higher activity to striped stem borer (Chilo suppressalis Walker) than parental lines in the laboratory bioassay. All pyramided lines and their hybrids exhibited excellent efficacy against stemborers and leaffolders in field evaluation, while most pyramided lines had no significant differences from original variety in yield under spraying of insecticide.
  
  
  CONCLUSIONS
  These results demonstrate that the two-gene lines have commercial potential and could serve as a valuable IRM strategy.
authors.affiliation: National Key Laboratory of Crop Genetic Improvement and National Centre of Plant Gene Research, Huazhong Agricultural University, Wuhan, PR China.
authors.forename: Zhou
authors.initials: Z
authors.lastname: Yang
authors.forename: Hao
authors.initials: H
authors.lastname: Chen
authors.forename: Wei
authors.initials: W
authors.lastname: Tang
authors.forename: Hongxia
authors.initials: H
authors.lastname: Hua
authors.forename: Yongjun
authors.initials: Y
authors.lastname: Lin
mesh_terms: D000818:Animals; D000083722:Bacillus thuringiensis Toxins; D001426:Bacterial Proteins / Q000235:genetics* / Q000276:immunology; D004731:Endotoxins / Q000235:genetics* / Q000276:immunology; D015870:Gene Expression; D006460:Hemolysin Proteins / Q000235:genetics* / Q000276:immunology; D007113:Immunity, Innate; D009036:Moths / Q000502:physiology; D012275:Oryza / Q000235:genetics / Q000276:immunology / Q000469:parasitology*; D010572:Pest Control, Biological / Q000379:methods*; D010935:Plant Diseases / Q000276:immunology / Q000469:parasitology*; D030821:Plants, Genetically Modified / Q000235:genetics* / Q000276:immunology / Q000469:parasitology
chemical_list: D000083722:Bacillus thuringiensis Toxins; D001426:Bacterial Proteins; D004731:Endotoxins; D006460:Hemolysin Proteins; C030956:insecticidal crystal protein, Bacillus Thuringiensis